Environews
NIEHS NEWS | Pesticides and Children
Animal studies have indicated that prenatal and early postnatal exposure to pollutants negatively affects respiratory health as well as physical and cognitive development. Researchers at children's health centers across the United States, jointly sponsored by the NIEHS and the U.S. Environmental Protection Agency, are conducting early-life studies to determine the effects of environmental exposures on human health. This article (p. A664) discusses work being done at four of these centers that evaluate and combat the effects of pesticides, among other pollutants.
FOCUS | Gender-Related Effects of EDCs
It's known that exposure to high doses of endocrine-disrupting chemicals (EDCs) can cause harmful health effects, but what, if any, are the adverse effects of low-dose exposure, especially during fetal development? Although some experts remain neutral while awaiting more conclusive evidence, two main camps of opinion disagree on the influence of low-dose exposure to EDCs. This article (p. A670) examines the ongoing debate between those who say there is no cause for alarm, and others who cite evidence of abnormalities in human sexuality, gender development and behaviors, reproductive capabilities, and sex ratios.
SPHERES OF INFLUENCE | Draft European Guidance on Pharmaceuticals
Pharmaceuticals, although a boon to fighting disease, may be a danger to environmental and human health when they end up in waterways. To help control the dispersal of these chemical compounds into the environment, the European Medicines Agency (EMEA) has drafted guidance for an environmental risk assessment procedure to accompany pharmaceutical companies' applications to market new drugs. This article (p. A678) describes details of the EMEA guidance, compares it to a similar protocol used in the United States, and discusses the possible benefits and limitations.
INNOVATIONS | Alternatives to Lead-Tin Solder
Lead-tin solder is an established, reliable staple in electronic product manufacturing, but this staple is also a well-known environmental hazard. Now, motivated by the European Union ban of all lead use in electronic equipment by 1 July 2006, researchers are seeking less hazardous but equally reliable materials to use in solder. This article (p. A682) discusses the emerging science on possible alternatives to the lead-tin alloy that will keep electronic devices user-friendly both during and after their lifetime.
Commentary
RISK CHARACTERIZATION | Flaws of Hormesis for Public Health Decisions
Hormesis (low-dose stimulation, high-dose inhibition) is often used to promote the notion that while high-level exposures to toxic chemicals could be detrimental to human health, low-level exposures would be beneficial. Thayer et al. (p. 1271) evaluate the hormesis hypothesis and potential adverse consequences of incorporating low-dose beneficial effects into public health decisions, contending that the assumption that hormesis is generally adaptive is an oversimplification of complex biological processes.
Research
ENDOCRINE | ER-Mediated Activity of PCBs
The impact of polychlorinated biphenyls (PCBs) on estrogen signaling is not fully understood. Plísková et al. (p. 1277) used the ER-CALUX bioassayto determine estrogenic/antiestrogenic activities of the prevalent PCB congeners and mixtures isolated from human male serum samples collected from residents of an area with an extensive environmental contamination and compared the results with those from a neighboring background region in eastern Slovakia. The lower-chlorinated PCBs were estrogenic, whereas the prevalent higher-chlorinated PCB congeners and major PCB metabolites behaved as antiestrogens. Coplanar PCBs had no direct effect on estrogen receptor (ER) activation. The data suggest that it might be important to investigate the direct effects of PCBs on steroid hormone levels in heavily exposed subjects.
ENDOCRINE | Effects of Cigarette Smoking on Hormones
Cigarette smoke contains compounds that are thought to affect hormone activity. Windham et al. (p. 1285) measured urinary levels of the pituitary follicle-stimulating hormone (FSH) in a subset of menstrual cycles, selected by smoking status, with the time of transition between two cycles being of primary interest.The mean daily urinary FSH levels around the cycle transition were increased at least 30-35% with moderate smoking. Tobacco smoke may alter endocrine function, perhaps at the level of the ovary, which in turn affects release of the pituitary hormones. This endocrine disruption likely contributes to the associations of smoking with adverse reproductive outcomes, including menstrual dysfunction, infertility, and earlier menopause.
DEVELOPMENT | Developmental Chlorpyrifos Exposure
Developmental exposure to chlorpyrifos alters cell signaling in the brain and in peripheral tissues. Slotkin et al. (p. 1291) administered 1 mg/kg/day chlorpyrifos to rats on postnatal days 1-4, a regimen below the threshold for systemic toxicity. When tested in adulthood, chlorpyrifos-exposed animals displayed elevations in plasma cholesterol and triglycerides but no alterations in nonesterified free fatty acids or glycerol. This effect was restricted to males. Results also indicate that subtoxic neonatal chlorpyrifos exposure, devoid of effects on viability or growth and within the parameters of human fetal or neonatal exposures, produces a pattern for plasma lipids and insulin that resembles major risk factors for atherosclerosis and type 2 diabetes mellitus.
POPULATION HEALTH | Declining Human Sex Ratio
Members of the Aamjiwnaang First Nation community in Canada voiced concerns that there appeared to be fewer male children in their community in recent years. Mackenzie et al. (p. 1295) assessed the proportion of male births over the period 1984-2003 as part of a community-based participatory research project. The trend in the proportion of male live births of the Aamjiwnaang First Nation has been declining continuously from the early 1990s to 2003, from an apparently stable sex ratio before this time. A community health survey is currently under way to gather more information about the health of the Aamjiwnaang community and to investigate factors that could be contributing to the decreasing proportion of male births.
Also see Science Selections, p. A686
ENDOCRINE | Life Stage Sensitivity of Exposure to Wastewater in Roach
Surveys of U.K. rivers have indicated sexual disruption in populations of wild roach (Rutilus rutilus) living downstream from wastewater treatment works (WwTW). Liney et al. (p. 1299) investigated feminized responses to two estrogenic WwTWs in roach exposed during life stages of germ cell division (early life and the postspawning period). Concentration-dependent feminization of reproductive ducts occurred in male fish when the exposure occurred during early life but not in those exposed as adults.
Also see Science Selections, p. A686
EXPOSURE ASSESSMENT | Inuit Community Exposure to Toxic Trace Metals
Exposure to lead, cadmium, and mercury is high in many arctic Inuit communities because metals emitted from industrial and urban sources are distributed by atmospheric transport to remote regions and appear in local foods. Domestic waste treatment systems that accumulate metals in sediment provide an accurate historical record of changes in ingestion or inhalation. Hermanson and Brozowski (p. 1308) collected sediment cores from an arctic lake used for sewage treatment to identify the history of exposure to Pb, Cd, and Hg. The daily per-person Pb input in 1990 exceeded the tolerable daily intake (TDI) level. The Cd and Hg input were below the respective TDI levels at the time.
GENE POLYMORPHISM | ALAD Polymorphism and Susceptibility to Lead Toxicity
Chia et al. (p. 1313) examined six polymorphisms in the -aminolevulinic acid dehydratase (ALAD) single-nucleotide polymorphisms (SNPs) to determine if these SNPs could modify the relationship between blood lead (PbB) and renal parameters in a cross-sectional study of lead-exposed workers in Vietnam. The authors applied analysis of covariance with interaction of PbB SNPs to examine the modifying effect of SNPs on the association of renal parameters and PbB, adjusting for potential confounders. The HpyCH4 SNP appeared to modify the lead toxicity to kidney, with the wild-type allele being more susceptible than variants.
TOXICOLOGY | Biomarkers in a Fish-Eating Population
A fish-eating population living near the St. Lawrence River displays a high body burden of polychlorinated biphenyls (PCBs) and dioxin-like compounds (DLCs). Ayotte et al. (p. 1318) measured biomarkers of liver enzyme induction and the relationship with organochlorine body burden in adult volunteers from this population. Neither DLC concentrations nor PCB-153 concentrations (representing total PCBs) were correlated with biomarkers of effects. Despite the high body burden of PCBs and DLCs in this population, only smoking had a significant correlation with biomarkers of hepatic enzyme induction. The data are consistent with smoking-induced liver CYP1A2 activity altering heme metabolism and increasing the biotransformation of mono-ortho PCB congeners.
POPULATION HEALTH | Fish Consumption and Advisory Awareness
More than 61 million adults live in the eight U.S. states bordering the Great Lakes (GL). Imm et al. (p. 1325) conducted a survey of adults living in GL states to assess their consumption of commercial and sport-caught fish and their awareness of state-issued consumption advisories. Survey findings indicate that exposure to persistent contaminants found in GL fish is likely limited to a relatively small subpopulation of avid sport-fish consumers. Results underscore the importance of fish advisories, because an estimated 2.9 million adults living in GL states may be at risk of exceeding the reference doses for methylmercury, polychlorinated biphenyls, and other bioaccumulative contaminants.
CARDIOVASCULAR | Enhancement of Vasoconstriction Induced by Arsenic
Chronic arsenic exposure causes cardiovascular diseases such as hypertension. Lee et al. (p. 1330) examined whether arsenic affected the contraction of aortic rings in an isolated organ bath system. Treatment with arsenite, a trivalent inorganic species, increased vasoconstriction induced by phenylephrine or serotonin in a concentration-dependent manner. Hypercontraction by arsenite was correlated with the extent of myosin light chain (MLC) phosphorylation stimulated by phenylephrine. Further results suggest that arsenite increases agonist-induced vasoconstriction mediated by MLC phosphorylation in smooth muscles and that calcium sensitization is one of the key mechanisms for the hypercontraction induced by arsenite in blood vessels.
EXPOSURE ASSESSMENT | Elevated perc in Low-Income, Minority Neighborhoods
Tetrachloroethylene (PCE, perc) emissions from dry cleaners operating in apartment buildings can contaminate residential indoor air. McDermott et al. (p. 1336) determined indoor air perc levels during 2001-2003 in 65 apartments located in 24 buildings in New York City, where dry cleaners used perc on-site. The mean apartment perc level was 10-fold lower than mean apartment levels documented before 1997. Despite these accomplishments, perc levels in 17 sampled apartments still exceeded the New York State Department of Health residential air guideline. Mean indoor air perc levels in minority neighborhoods were four times higher than in nonminority households.
EXPOSURE ASSESSMENT | Sources of Lead in Cocoa and Chocolate
Rankin et al. (p. 1344) present lead concentrations and isotopic compositions from analyses of cocoa beans, shells, and soils from six Nigerian cocoa farms and analyses of manufactured cocoa and chocolate products. The average lead concentration of cocoa beans was ≤ 0.5 ng/g, which is one of the lowest reported values for a natural food. Lead concentrations of manufactured cocoa and chocolate products were as high as 230 ng/g and 70 ng/g, respectively, which are consistent with surveys listing lead concentrations in chocolate products among the highest reported for foods. Most contamination occurs during shipping and/or processing of the cocoa beans and the manufacture of cocoa and chocolate products.
Also see Science Selections, p. A687
CARDIOVASCULAR | Cardiac Apoptotic Effects of Second-Hand Smoke
Although environmental tobacco smoke (ETS) is linked to heart disease in nonsmokers, the molecular mechanism of pathogenesis is unknown. Kuo et al. (p. 1349) found that exposure to ETS at various doses for 30 min twice a day for 1 month produced a dose-dependently reduced heart weight to body weight ratio and enhanced interstitial fibrosis. Results of further gene expression analyses indicate that the effects of ETS on cardiomyocytes are mediated by the Fas death-receptor-dependent apoptotic pathway and might be related to the incidence of cardiac disease in ETS-exposed nonsmokers.
TOXICOGENOMICS | Gene Expression Profiles of Rat Thyroid Toxicity
Organic iodides induce thyroid hypertrophy and increase alterations in colloid in rats. Glatt et al. (p. 1354) evaluated the effect of free iodide (as sodium iodide) on thyroid toxicity compared with phenobarbital (PB) and propylthiouracil (PTU). Thyroid gene expression analyses using Affymetrix U34A GeneChips, a regularized t-test, and Gene Map Annotator and Pathway Profiler demonstrated significant changes in rhodopsin-like G-protein-coupled receptor transcripts for all chemicals. NaI demonstrated dose-dependent changes in multiple oxidative stress-related genes. Differential transcript profiles, possibly relevant to follicular cell tumor outcomes, were observed in rats exposed to PB and PTU, including genes involved in Wnt signaling and ribosomal protein expression.
FETAL DEVELOPMENT | Risk of Congenital Anomalies and Landfill Sites
There has been concern that living near a particular landfill site in Wales caused increased risk of births with congenital malformations. Palmer et al. (p. 1362) examine whether residents living close to 24 landfill sites in Wales experienced increased rates of congenital anomalies after the landfills opened compared with before they opened. The ratio of the observed to expected rates of congenital anomalies before landfills opened was 0.87, and this increased to 1.21 after opening, giving a standardized risk ratio of 1.39. Causal inferences are difficult because of incomplete case ascertainment, lack of data on individual-level exposures, and other socioeconomic and lifestyle factors that may confound a relationship with area of residence.
Environmental Medicine
RISK CHARACTERIZATION | Beryllium Exposure-Response Study
Rosenman et al. (p. 1366) conducted a medical screening for beryllium disease among former workers of a beryllium processing facility. The prevalence of definite or probable chronic beryllium disease (CBD) was 7.6%, and another 7.0% were sensitized to beryllium. The level of CBD and sensitization in the cohort was greater than reported in studies of other beryllium-exposed cohorts. Both CBD and sensitization occurred in former workers whose mean daily working lifetime average exposures were lower than the current allowable Occupational Safety and Health Administration workplace air level of 2 µg/m3 and the Department of Energy guideline of 0.2 µg/m3.
INFECTIOUS DISEASE | Occupational Varicella Recurrence
Common outcomes of varicella-zoster virus (VZV) infections include chickenpox (primary) and shingles (recurrence or latency), as well lifetime immunity against chickenpox. Ku et al. (p. 1373) report the case of a registered nurse who worked in a neurologic surgery ward in a general hospital in Taipei, Taiwan. She developed recurrent chickenpox after caring for a paraparesis patient who had herpes zoster during hospitalization in 2002. Recent negative specific serum IgM and positive specific serum IgG indicated a past VZV infection. Occupational VZV hazards exist in health care environments; therefore, testing for VZV antibody and a VZV vaccination program for susceptible health care workers is suggested.
Children's Health
FETAL DEVELOPMENT | Fish, Mercury, and Infant Cognition
Fish and other seafood may contain organic mercury but also beneficial nutrients such as n-3 polyunsaturated fatty acids. Oken et al. (p. 1376) examined associations of maternal fish intake during pregnancy and maternal hair mercury at delivery with infant cognition among mother-infant pairs. Infant cognition was tested by the percent novelty preference on visual recognition memory (VRM) at 6 months of age. Higher fish intake was associated with higher infant cognition. However, an increase of 1 ppm mercury was associated with a decrement in VRM score. Women should continue to eat fish during pregnancy but choose varieties with lower mercury contamination.
Also see Science Selections, p. A688
EXPOSURE ASSESSMENT | Methyl and Inorganic Mercury during Breast-feeding
Methylmercury (MeHg) and mercury vapor are known to cross the placental barrier, but little is known about infant exposure via breast milk. Björnberg et al. (p. 1381) measured MeHg and inorganic mercury (I-Hg) in blood of mothers and their infants, and total mercury (T-Hg) in breast milk up to 13 weeks postpartum. Infant blood MeHg was associated with maternal blood MeHg at delivery and decreased until 13 weeks of age. Infant blood I-Hg was associated with maternal blood I-Hg at delivery and decreased until 13 weeks of age. Exposure to both forms of mercury is higher before birth, and MeHg seems to contribute more to infant exposure postnatally via breast milk than I-Hg.
OXIDATIVE STRESS | Association of DNA Oxidative Stress and Metal Exposure
The health effects of arsenic, chromium, and nickel exposures are equivocal for children. Wong et al. (p. 1386) performed a cross-sectional study to investigate possible associations between the internal concentrations of As, Cr, and Ni and oxidative stress to DNA in children. The median urinary 8-hydroxy-2´-deoxyguanosine (8-OHdG) level was 11.7 ng/mg creatinine. There was no relationship between urinary Ni and 8-OHdG. Children with high urinary Cr and As had greater urinary 8-OHdG than did those with lower urinary Cr and As. Children with both high urinary As and Cr had the highest 8-OHdG levels in urine.
IMMUNE | Air Pollution and Cord Lymphocyte Phenotypes
Hertz-Picciotto et al. (p. 1391) examined short-term associations of air pollution exposures with lymphocyte immunophenotypes in cord blood among deliveries in the Czech Republic. Fine particulate matter < 2.5 µm in diameter (PM2.5) and 12 polycyclic aromatic hydrocarbons (PAHs) in 24-hr samples were measured. Cord blood samples were analyzed to determine phenotypes of CD3+ T lymphocytes and their subsets CD4+ and CD8+, CD19+ B lymphocytes, and natural killer cells. Average PAH or PM2.5 levels during the 14 days before birth were associated with decreases in T-lymphocyte phenotype fractions and a clear increase in the B-lymphocyte fraction. Ambient air pollution may influence the relative distribution of lymphocyte immunophenotypes of the fetus.
EXPOSURE ASSESSMENT | Sources and Factors that Determine Indoor Phthalate Concentrations
A recent study reported associations between asthma symptoms and the concentrations of n-butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in dust taken from childrens' bedrooms. Bornehag et al. (p. 1399) examined associations between these phthalate esters in the dust characteristics of the home. There were associations between concentrations of both BBzP and DEHP and the amount of polyvinyl chloride used as flooring and wall material in the home. The associations may help identify homes where phthalate concentrations are likely to be elevated and may aid in developing mitigation strategies.
RESPIRATORY DISEASE | Fungal Levels and Allergic Rhinitis
Sensitization to fungi, such as Alternaria, is associated with allergic rhinitis and asthma in children. Stark et al. (p. 1405) examined high in-home fungal concentrations (> 90th percentile) measured once within the first 3 months of life in a prospective birth cohort of children of asthmatic/allergic parents as predictors of doctor-diagnosed allergic rhinitis in the first 5 years of life. Predictors of allergic rhinitis included high levels of dust-borne Aspergilluss, Aureobasidium, and yeasts. High fungal concentrations and reports of water damage, mold, or mildew in homes may predispose children with a family history of asthma or allergy to the development of allergic rhinitis.
IMMUNE | Maternal Smoking and Breast Milk Interleukin-1
Zanardo et al. (p. 1410) compared the colostral and transitional milk concentrations of interleukin-(IL)1 and immunomodulators β-endorphin and leptin among smoking and nonsmoking mothers. IL-1 concentrations were significantly reduced in the colostrum of smoking mothers. Colostral β-endorphin and leptin concentrations were comparable. No significant differences were found between smoking and nonsmoking lactating mothers in transitional milk concentrations of IL-1, β-endorphin, and leptin. Moreover, β-endorphin and leptin concentrations were significantly reduced in transitional milk samples compared with colostrum from both smoking and nonsmoking mothers. The altered level of IL-1 increases our understanding of how breast-feeding could be nonprotective against infections among the neonates nursed by smoking mothers.
Mini-Monograph
CHILDREN'S HEALTH | Lessons Learned: NIEHS/EPA Children's Centers
This mini-monograph (p. 1414) highlights the experiences of the National Institute of Environmental Health Sciences/U.S. Environmental Protection Agency Centers for Children's Environmental Health and Disease Prevention Research, focusing on areas of interest for the National Children's Study. These include general methodologic issues for conducting longitudinal birth cohort studies and community-based participatory research and for measuring air pollution exposures, pesticide exposures, asthma, and neurobehavioral toxicity. This explication of lessons learned provides an opportunity for the planners of the National Children's Study to utilize information on what has and has not worked when studying diverse multiracial and multiethnic groups of children with unique urban and rural exposures.